23
WIKA operating instructions, model CTH6200
EN
2146872.02 07/2021 EN/DE
6. Commissioning, operation
For measurements of temperatures that are close to the switching limits, it may be more
convenient to maintain a certain resolution, e.g. to facilitate logging.
In this case, select the appropriate resolution.
6.3.3 Compensation characteristic (
Lin
E
.
751
)
This function uses the standard conversion resistance to temperature in accordance with
EN 60751 (
Lin
E
.
751
). Other linearisations can also be used.
User characteristic curve can be read out and written back with GSoft evaluation
software.
The characteristic curve consists of a table (resistance [Ohm] / temperature [°C]) with a
total of 50 value pairs.
The characteristic curve in accordance with EN 60751 uses the temperature
scale ITS90 and the following calculation formula:
Temperatures < 0 °C:
R
neg
(T) = 100 [1 + 3.908310
-3
* T - 5.77510
-7
* T
2
- 4.18310
-12
* (T - 100) * T
3
]
Temperatures ≥ 0 °C:
R
pos
(T): = 100 (1 + 3.908310
-3
* T - 5.77510
-7
* T2)
Please note!
Temperature measurements with a user characteristic curve may only be
carried out in the temperature range for which the user characteristic curve
was determined. Measurements with a user characteristic curve outside the
calibrated range can lead to large measuring deviations. For measurements
outside the checked range, the characteristic curve must therefore be set in
accordance with DIN EN 60751 (
Lin
E
.
751
).
6.3.4 Zero point correction/offset (
OFfS
)
The zero point correction, together with the slope correction, is mainly used for the
adjustment of probe deviations.
For temperature measurement, a zero point correction can be made:
Displayed temperature = measured temperature - offset
